A typical known Cellular Telephone Base Station System comprises several elements, including one or more panel antennas, each panel antenna comprising an array of radiating elements mounted at an elevation above the ground, and base station electronics mounted remotely from the antenna arrays. The known antenna arrays typically include a plurality of radiating elements and a feed network. The radiating elements and feed network may be mounted on a panel antenna plate. See, e.g., U.S. Pat. No. 6,034,649, titled Dual Polarized Base Station Antenna. In some antennas, a ground plane for the radiating elements may be used as a part of the antenna structure. In some known panel antennas, the feed network may include power dividers, phase shifters, or other circuit devices for adjusting beam width and/or beam direction. Typically, however, such known panel antennas have feed networks which comprise passive components, and do not have active devices which perform power amplification.
Typically, the known panel antennas are driven by a Low Noise Amplifier (LNA). A LNA may be mounted on support structure for the panel antenna or located as part of a base station, comprising an environmental enclosure on the ground below the panel antenna. The LNA may be coupled to the feed network of the panel antenna by coaxial cable. Locating the LNA in the environmental enclosure at the base station facilitates protecting active electronics from the elements. However, such an arrangement also requires extensive cabling from the base station environmental enclosure to the location of the panel antenna, which may be located at a significant elevation above the base station.
Another type of panel antenna is one where individual radio elements are associated with the radiating elements. For example, international patent application WO 2008/1009421, titled “Antenna Array System,” discloses an all-digital antenna array. WO 2008/1009421 is incorporated by reference. In the '421 application, a digital signal is provided to a Communications Hub. The Communications Hub distributes the digital signal to a plurality of micro radios. An antenna radiating element is associated with each micro radio. However, the '421 patent application does not consider or solve certain issues with packaging and antenna design.
For example, in prior art remote radio head antennas, the components in the panel antenna are passive and heat dissipation is not an issue. In the '421 application, however, each micro radio has a power digital to analog converter for converting the digital signal into an RF signal. This power converter generates a significant amount of heat that must be dissipated. The '421 application does not teach or suggest a way to solve the heat dissipation problem. Additionally, locating active electronic components, including power amplifiers in the panel antenna raises substantial issues regarding protecting such electronics from adverse environmental conditions, such as rain and other forms of precipitation. Protection from environmental conditions is not solved in the '421 application. Also, the '421 application does not address issues concerning electromagnetic interference, manufacturing assembly and serviceability.